Anything you got about those email addresses would be tossed. There are things that have to be followed in order for the police to be able to use the evidence. They have the ability via the law to get more information.

If you really need to show that you were defrauded. What you need to do is get the emails you were sent (anything they emailed too you), the receipts you have from buying the said products, and any other information you already have in your possession. Then go down to the local station and ask to file a report.

Your best bet would be to turn the information over to the proper authorities. Unfortunately, they may not be able to help you, but that is the correct approach. Not to mention, the legality and ethics of counter-hacking is questionable.

A friendly suggestion, it might also be a good idea to evaluate your companies procedures to prevent this sort of thing from happening in the future. I know it sucks to be ripped off, but you could take something positive from the situation.

Basically, as much as you'd like to get your money back and get revenge on the culprit, in the end you'll do yourself a big favor by letting it go, never contacting them again and don't try to find them. I've seen documentaries like Dateline where the investigative journalist travelled the globe following every lead to find the scammer (because the authorities wouldn't help him) and actually met face-to-face with him. In the end, the journalist was frustrated, because the man just walked. There was nothing that could be done, even with the clout & money of a large media company.

So as unfortunate as it may be, you don't have anywhere near the funds or the power to make this happen. It's totally unfair, but that's just the way it is.